1/* Copyright (c) 2002,2003 CrystalClear Software, Inc. 2 * Use, modification and distribution is subject to the 3 * Boost Software License, Version 1.0. (See accompanying 4 * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) 5 * Author: Jeff Garland, Bart Garst 6 * $Date$ 7 */ 8 9#ifndef NO_BOOST_DATE_TIME_INLINE 10 #undef BOOST_DATE_TIME_INLINE 11 #define BOOST_DATE_TIME_INLINE inline 12#endif 13 14namespace boost { 15namespace date_time { 16 //! Return the day of the week (0==Sunday, 1==Monday, etc) 17 /*! Converts a year-month-day into a day of the week number 18 */ 19 template<typename ymd_type_, typename date_int_type_> 20 BOOST_DATE_TIME_INLINE 21 unsigned short 22 gregorian_calendar_base<ymd_type_,date_int_type_>::day_of_week(const ymd_type& ymd) { 23 unsigned short a = static_cast<unsigned short>((14-ymd.month)/12); 24 unsigned short y = static_cast<unsigned short>(ymd.year - a); 25 unsigned short m = static_cast<unsigned short>(ymd.month + 12*a - 2); 26 unsigned short d = static_cast<unsigned short>((ymd.day + y + (y/4) - (y/100) + (y/400) + (31*m)/12) % 7); 27 //std::cout << year << "-" << month << "-" << day << " is day: " << d << "\n"; 28 return d; 29 } 30 31 //!Return the iso week number for the date 32 /*!Implements the rules associated with the iso 8601 week number. 33 Basically the rule is that Week 1 of the year is the week that contains 34 January 4th or the week that contains the first Thursday in January. 35 Reference for this algorithm is the Calendar FAQ by Claus Tondering, April 2000. 36 */ 37 template<typename ymd_type_, typename date_int_type_> 38 BOOST_DATE_TIME_INLINE 39 int 40 gregorian_calendar_base<ymd_type_,date_int_type_>::week_number(const ymd_type& ymd) { 41 unsigned long julianbegin = julian_day_number(ymd_type(ymd.year,1,1)); 42 unsigned long juliantoday = julian_day_number(ymd); 43 unsigned long day = (julianbegin + 3) % 7; 44 unsigned long week = (juliantoday + day - julianbegin + 4)/7; 45 46 if ((week >= 1) && (week <= 52)) { 47 return week; 48 } 49 50 if (week == 53) { 51 if((day==6) ||(day == 5 && is_leap_year(ymd.year))) { 52 return week; //under these circumstances week == 53. 53 } else { 54 return 1; //monday - wednesday is in week 1 of next year 55 } 56 } 57 //if the week is not in current year recalculate using the previous year as the beginning year 58 else if (week == 0) { 59 julianbegin = julian_day_number(ymd_type(static_cast<unsigned short>(ymd.year-1),1,1)); 60 juliantoday = julian_day_number(ymd); 61 day = (julianbegin + 3) % 7; 62 week = (juliantoday + day - julianbegin + 4)/7; 63 return week; 64 } 65 66 return week; //not reachable -- well except if day == 5 and is_leap_year != true 67 68 } 69 70 //! Convert a ymd_type into a day number 71 /*! The day number is an absolute number of days since the start of count 72 */ 73 template<typename ymd_type_, typename date_int_type_> 74 BOOST_DATE_TIME_INLINE 75 date_int_type_ 76 gregorian_calendar_base<ymd_type_,date_int_type_>::day_number(const ymd_type& ymd) 77 { 78 unsigned short a = static_cast<unsigned short>((14-ymd.month)/12); 79 unsigned short y = static_cast<unsigned short>(ymd.year + 4800 - a); 80 unsigned short m = static_cast<unsigned short>(ymd.month + 12*a - 3); 81 unsigned long d = ymd.day + ((153*m + 2)/5) + 365*y + (y/4) - (y/100) + (y/400) - 32045; 82 return d; 83 } 84 85 //! Convert a year-month-day into the julian day number 86 /*! Since this implementation uses julian day internally, this is the same as the day_number. 87 */ 88 template<typename ymd_type_, typename date_int_type_> 89 BOOST_DATE_TIME_INLINE 90 date_int_type_ 91 gregorian_calendar_base<ymd_type_,date_int_type_>::julian_day_number(const ymd_type& ymd) 92 { 93 return day_number(ymd); 94 } 95 96 //! Convert year-month-day into a modified julian day number 97 /*! The day number is an absolute number of days. 98 * MJD 0 thus started on 17 Nov 1858(Gregorian) at 00:00:00 UTC 99 */ 100 template<typename ymd_type_, typename date_int_type_> 101 BOOST_DATE_TIME_INLINE 102 date_int_type_ 103 gregorian_calendar_base<ymd_type_,date_int_type_>::modjulian_day_number(const ymd_type& ymd) 104 { 105 return julian_day_number(ymd)-2400001; //prerounded 106 } 107 108 //! Change a day number into a year-month-day 109 template<typename ymd_type_, typename date_int_type_> 110 BOOST_DATE_TIME_INLINE 111 ymd_type_ 112 gregorian_calendar_base<ymd_type_,date_int_type_>::from_day_number(date_int_type dayNumber) 113 { 114 date_int_type a = dayNumber + 32044; 115 date_int_type b = (4*a + 3)/146097; 116 date_int_type c = a-((146097*b)/4); 117 date_int_type d = (4*c + 3)/1461; 118 date_int_type e = c - (1461*d)/4; 119 date_int_type m = (5*e + 2)/153; 120 unsigned short day = static_cast<unsigned short>(e - ((153*m + 2)/5) + 1); 121 unsigned short month = static_cast<unsigned short>(m + 3 - 12 * (m/10)); 122 year_type year = static_cast<unsigned short>(100*b + d - 4800 + (m/10)); 123 //std::cout << year << "-" << month << "-" << day << "\n"; 124 125 return ymd_type(static_cast<unsigned short>(year),month,day); 126 } 127 128 //! Change a day number into a year-month-day 129 template<typename ymd_type_, typename date_int_type_> 130 BOOST_DATE_TIME_INLINE 131 ymd_type_ 132 gregorian_calendar_base<ymd_type_,date_int_type_>::from_julian_day_number(date_int_type dayNumber) 133 { 134 date_int_type a = dayNumber + 32044; 135 date_int_type b = (4*a+3)/146097; 136 date_int_type c = a - ((146097*b)/4); 137 date_int_type d = (4*c + 3)/1461; 138 date_int_type e = c - ((1461*d)/4); 139 date_int_type m = (5*e + 2)/153; 140 unsigned short day = static_cast<unsigned short>(e - ((153*m + 2)/5) + 1); 141 unsigned short month = static_cast<unsigned short>(m + 3 - 12 * (m/10)); 142 year_type year = static_cast<year_type>(100*b + d - 4800 + (m/10)); 143 //std::cout << year << "-" << month << "-" << day << "\n"; 144 145 return ymd_type(year,month,day); 146 } 147 148 //! Change a modified julian day number into a year-month-day 149 template<typename ymd_type_, typename date_int_type_> 150 BOOST_DATE_TIME_INLINE 151 ymd_type_ 152 gregorian_calendar_base<ymd_type_,date_int_type_>::from_modjulian_day_number(date_int_type dayNumber) { 153 date_int_type jd = dayNumber + 2400001; //is 2400000.5 prerounded 154 return from_julian_day_number(jd); 155 } 156 157 //! Determine if the provided year is a leap year 158 /*! 159 *@return true if year is a leap year, false otherwise 160 */ 161 template<typename ymd_type_, typename date_int_type_> 162 BOOST_DATE_TIME_INLINE 163 bool 164 gregorian_calendar_base<ymd_type_,date_int_type_>::is_leap_year(year_type year) 165 { 166 //divisible by 4, not if divisible by 100, but true if divisible by 400 167 return (!(year % 4)) && ((year % 100) || (!(year % 400))); 168 } 169 170 //! Calculate the last day of the month 171 /*! Find the day which is the end of the month given year and month 172 * No error checking is performed. 173 */ 174 template<typename ymd_type_, typename date_int_type_> 175 BOOST_DATE_TIME_INLINE 176 unsigned short 177 gregorian_calendar_base<ymd_type_,date_int_type_>::end_of_month_day(year_type year, 178 month_type month) 179 { 180 switch (month) { 181 case 2: 182 if (is_leap_year(year)) { 183 return 29; 184 } else { 185 return 28; 186 }; 187 case 4: 188 case 6: 189 case 9: 190 case 11: 191 return 30; 192 default: 193 return 31; 194 }; 195 196 } 197 198 //! Provide the ymd_type specification for the calandar start 199 template<typename ymd_type_, typename date_int_type_> 200 BOOST_DATE_TIME_INLINE 201 ymd_type_ 202 gregorian_calendar_base<ymd_type_,date_int_type_>::epoch() 203 { 204 return ymd_type(1400,1,1); 205 } 206 207 //! Defines length of a week for week calculations 208 template<typename ymd_type_, typename date_int_type_> 209 BOOST_DATE_TIME_INLINE 210 unsigned short 211 gregorian_calendar_base<ymd_type_,date_int_type_>::days_in_week() 212 { 213 return 7; 214 } 215 216 217} } //namespace gregorian 218 219 220